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This article describes a procedure for fabricating an optimal provisional restoration before tooth preparation. The procedure involves the fabrication of an indirect-direct provisional fixed partial denture. There are several advantages to this procedure, such as reduced chair time, less heat generated in the mouth, reduced contact between resin monomer and soft tissues, and optimal esthetics.
Teeth that have lost a good portion of alveolar support can be stabilized and maintained by the use of endodontic endosseous implants. Two hopeless cases were restored to function with ceramic-coated, custom-fabricated chrome-cobalt implants. The technique for fabrication is described.
PURPOSE: Dental implant placement in atrophic alveolar ridges often necessitates grafting procedures, followed by immediate or delayed implant placement. This study assessed the survival of immediately loaded dental implants placed in deficient alveolar bone sites at bone grafting. MATERIALS: From 1999 to May 2002, 1 operator (A.P.) inserted 1065 implants (607 in mandibles, 458 in maxillae) into 338 partially edentulous patients. Most implants were placed into compromised residual ridges or prepared tooth extraction sockets. Implants placed in augmented areas were splinted to implants in nonaugmented sites for stability. In all cases, beta-tricalcium phosphate was mixed with blood from the surgical site to augment the ridge level or fill spaces between the implant and socket wall. When indicated, the same materials were used for sinus floor augmentation. All implants were tapered screws with roughened surfaces, primarily (75%) from 1 manufacturer. One of the authors (Z.O.) prosthetically restored a total of 189 implants that were placed in 35 patients. In this group of patients, complete restorative data were available. All implants were monitored for 12-48 months (mean = 19.2; median = 24). RESULTS: A total of 1039 implants survived, and 26 failed, including 5 in the anterior mandible and 21 in the maxillae. In the restorative group, 186 implants survived, and 3 maxillary implants failed. All implant failures in this study occurred in the augmented sites. CONCLUSION: Within the limitations of this study, immediate loading of splinted implants in augmented sites is a predictable procedure.
The aim of this study was to collect information about the mean working time needed to accomplish the clinical procedures in applying an adhesive bridge, and to gain an insight into the factors that influence the working time. The study was carried out as part of a clinical trial. One hundred and fifty-one patients needing one adhesive bridge were selected for this study and divided between five operators. Clinical procedures were carried out following a written protocol. The statistical method consisted of an ANOVA after log-transformation of the working times. The total mean working time needed to accomplish the clinical procedures for adhesive bridges was 60.7 min (s.d. +/- 16.5 min). The mean working time increased by 30% where the abutment teeth were restored with class II or class III restorations. No influence was found related to: type of bridge (i.e. macromechanical versus micromechanical), type of luting resin and location of the bridge. A significant effect on the working times was found for: operator, tooth preparation and occlusal adjustments. With increasing experience of the operator the median working time decreased by up to 35%. The data from this study are considered as useful basic information for efficient planning in the dental practice and for a further cost-benefit analysis.
A total of 203 resin-bonded bridges was inserted under controlled clinical conditions and evaluated for a number of patient-dependent variables over a period of 5 years. Of the variables evaluated only 'initial occlusion of the abutment teeth' and 'location in the dental arch' had a significant influence on the retention of resin-bonded bridges. Anterior resin-bonded bridges were more durable than posterior bridges. Mandibular posterior bridges showed the lowest retention ratio. It is concluded that the design of posterior resin-bonded bridges should include tooth preparation or a wrap-around design of the retainers.
The problems encountered in casting titanium in dentistry have not been completely resolved. The Procera system forms crowns by means of a combination of spark-erosion and milling. The accuracy of fit was examined before and after ceramic veneering both in vitro and in vivo. Before veneering, on conical surfaces space widths were approximately 53 microns in vitro and 69 microns in vivo. At shoulders and occlusal surfaces, spaces of about 430 microns were measured in vitro and of about 500 microns were measured in vivo. After ceramic veneering, slight increases in space widths could be observed. The metal-ceramic compound was tested by the 3-point bending test (DIN) and the bending test (ISO). The DIN test was satisfactory, but not the ISO test. It is concluded that titanium crowns processed by the Procera System are suitable for clinical usage, if the space widths at shoulders and the occlusal surface and the special requirements of tooth preparation are taken into account.
It has been reported in the literature that impingement of the casting at the axial-occlusal line angle of the tooth preparation may be a major cause of incomplete seating following cementation. It has been suggested that an additional coat of spacer applied to these areas on the laboratory die before the fabrication of the casting may alleviate this discrepancy. This study evaluated the effect of three die spacer placement techniques on the seatability of cemented castings. Results showed no statistical difference in seating between castings made with conventional relief and those made with additional relief at the axial-occlusal line angles. Castings relieved exclusively at the axial-occlusal line angles exhibited significant post-cementation marginal openings.
In a longitudinal clinical trial the treatment times needed for the fabrication of Posterior Resin-Bonded Bridges (PRBB's) were recorded and analyzed. From a total of 200 PRBB's with different designs and retention systems, 152 were selected for this analysis. The selected bridges were made by 12 operators: 3 university staff members and 9 general practitioners. The mean treatment time for PRBB's was 80 min. When posterior composite restorations were made in the abutment teeth, the mean treatment time increased by 25% up to 100 min. From the factors which were considered to influence the treatment time, a significant effect was found for "restorations", "operator" and "experience of the operator". The other factors considered, such as "tooth preparation", "retention system", "isolation method", "occlusion", and "location", showed no detectable effect on the treatment time. The results of this study are considered to be useful in further cost-benefit analyses.
Dentin bonding using the total-etch method has been claimed to be technique-sensitive. The aim of this study is to examine the effect of acid-etch variations on the dentin demineralization and interfacial structure of the adhesive-dentin bond using a differential staining technique. Single Bond adhesive with 35% phosphoric acid gel was used. The occlusal one-third of the crown was removed from 60 extracted, unerupted human third molars. Smear layers were created by abrading the dentin with 600 grit SiC under water for 30 s. The prepared teeth were randomly assigned to four groups according to etching time (Group 1, 10 s; Group 2, 15 s; Group 3, 30 s; Group 4, 60 s). In each group, the etching gel was: (i) applied and spread to the dentin surface and left to stand undisturbed; (ii) applied and gently agitated during etching; (iii) applied without using dispensing tips for the syringe and left for the same period as above. After rinsing, the etched dentin was then treated with the adhesive per manufacturers' instructions. 3-5 micro m thin sections of the adhesive/dentin (a/d) interface were cut with a microtome and stained with Goldner's trichrome. Stained, thin sections from each prepared tooth were imaged with light microscopy. The depth and extent of dentin demineralization, and the a/d interdiffusion zone were clearly visible by this differential staining microtechnique. The thickness of the interdiffusion zone increased as a function of etching time. However, the etchant gel application methods have a significant influence on dentin demineralization. Although agitating acid gel facilitates the penetration and etching into dentin, it should not be recommended, especially for longer etching time. These results indicated that the etching technique has a large effect on the profile of both dentin demineralization and interfacial structure.
OBJECTIVE: The aim of this study was to evaluate the effect of the treatment of sodium hypochlorite (NaOCl) after acid conditioning of the enamel and dentin of the primary teeth affected with hypocalcified amelogenesis imperfecta (HCAI) on the shear bond strength of the composite material. MATERIALS AND METHODS: Primary teeth from a 12-year-old girl affected with HCAI and primary teeth collected from apparently healthy children were used. A total of four groups, experimental and control with and without NaOCl treatment were specified. In the control group conventional composite procedure was performed and in the treatment group 5% NaOCl was applied after acid conditioning and then the procedure continued as in the control group. RESULTS: In teeth affected with HCAI, enamel shear bond strengths were significantly enhanced in the treatment group compared with the conventional procedure. CONCLUSION: Deproteinization could be attributed as effective in enhancing the enamel bonding in HCAI teeth and could be used to overcome the high failure rates of adhesive restorations in HCAI cases.
The elimination of the labiogingival metal collar of a porcelain-fused-to-metal (PFM) restoration is an attempt to achieve an improved esthetic result. In their expectation of a more cosmetic tooth restoration, patients may influence dentists to use the all-porcelain labial margin to avoid metal showing in the final restoration. Success of this type of restoration depends upon proper tooth preparation. The all-porcelain margin requires a 1.2-mm wide labiogingival shoulder of approximately 70 or 90 degrees wrapping into the interproximal area. Much of the effectiveness of the restoration depends upon the design of the metal substructure. The following change is made in the design of this substructure for this modified PFM crown: the labiogingival portion of the metal is finished back to the gingival-pulpal line angle with the metal against the axial wall being from 0.3 mm to 0.5 mm thick. This allows for 0.2 to 0.3 mm of opaque and 0.7 to 1.0 mm of shoulder porcelain. The direct lift-off technique is a useful method of achieving clinically acceptable all-porcelain margins. Such restorations may give excellent results.
UNLABELLED: In restorative dentistry direct composite resin materials can be used to conservatively resolve many esthetic problems. Opaque resins are often necessary to mask discolorations and/or dark backgrounds when restoring anterior teeth. This article presents a direct composite resin veneer technique using opaquers. Potential problems with the tone of restorations after the use of opaquers are discussed. Advantages, limitations, and the clinical technique are presented. Training, as well as attention to the technique, contributes to an acceptable result. CLINICAL SIGNIFICANCE: Resinous opaquers can be used as a valid adjunct to the direct composite resin veneer technique when conservatively restoring dark teeth.
An interesting case of post-insertion sensitivity in a patient who had an etched cast metal prosthesis (Maryland Bridge) cemented with a recently marketed resin luting agent is discussed. This case report draws attention to the fact that despite the relative conservatism and simplicity commonly associated with abutment tooth preparation for resin bonded prostheses, dentine exposure should be avoided if possible to reduce the potential for chemical irritation of the pulp by components of the resin luting system.
Recent studies have investigated a mercury-free silver alternative to amalgam, but the silver powders required a relatively high compaction pressure to consolidate. The aim of the present study was to consolidate a precipitated silver powder into a cohesive solid using an air-driven pneumatic condenser fitted with an amalgam plugger at a clinically realistic load, and to study the mechanisms and rates of three-body wear of the consolidated silver in comparison with that of an amalgam. The silver powder was annealed, rinsed with a dilute acid, and consolidated either in a prepared tooth cavity or in a specimen mold at a load of 15 N. A four-station wear machine was used where each specimen was immersed in a slurry containing polymethyl methacrylate beads, then a steel pin was loaded and rotated against the specimen at a maximum load of 76 N. The flexural strength in MPa (mean +/- SD; n = 10) was 86 +/- 20 for amalgam, 181 +/- 45 for silver with a polished surface, and 202 +/- 21 for silver with a burnished surface. After 4 x 10(5) wear cycles, the wear scar depth in microm was 134 +/- 54 for amalgam, 143 +/- 8 for polished silver, and 131 +/- 9 for burnished silver, which were not significantly different (Tukey's multiple comparison test; family confidence coefficient = 0.95). SEM examination revealed cracks and fracture pits in the worn surface of amalgam, in contrast to a smooth surface in silver. Wear and material removal in amalgam occurred by microfracture and dislodgement of cracked segments, while wear in the silver occurred by ductile deformation and flow of materials. To conclude, the consolidated silver possesses a three-body wear resistance similar to that of amalgam, and a higher resistance to wear-induced damage and cracking than amalgam. The mechanism of wear in amalgam is microfracture and material dislodgement, while that in consolidated silver is ductile deformation and flow of material.
State and regional board exams represent the final gateway to dental licensure. One would expect that the requirements for licensure would reflect procedures that are beneficial to each patient's oral health and that are consistent with the teachings of most dental schools. We conducted an Internet survey to determine whether Class 2 tooth preparations based on caries lesions whose radiolucencies were confined to enamel were allowed for state and regional exams. Information obtained for 46 of the 50 states revealed that 33 of the states (72%) allowed teeth with either an E1 or E2 lesion to be restored. Seventeen of these states allowed teeth with an E1 lesion to be restored. Only 12 of the 46 states (26%) covered by these boards did not allow teeth with E1 or E2 lesions to be surgically treated. In contrast, a recent report indicates that only 30% of dental schools permit teeth with enamel lesions to be restored to satisfy clinical requirements and competencies.
The creation of a natural-looking ceramic crown which blends harmoniously with the surrounding dentition is not merely a matter of recording a shade. The subtleties of colour, translucency, discrete staining, texture, lustre and shape are all essential features. Accurate shade taking and correct tooth preparation are all necessary elements but are of little value if the information cannot be precisely communicated to the technician.
In the fourth article in this series the techniques for carrying out pulp therapy and stainless steel restoration in primary molars are discussed. Early pulp involvement in primary molars means that pulp therapy and the use of appropriate coronal restoration, such as stainless steel crowns, are indispensable if repetitive restoration of primary molars is to be avoided. These techniques themselves are not difficult to carry out once the child's co-operation is established and should be well within the capability of any dentist with an interest in the dental care of children.
Modern post preparation techniques reflect a change from what was once considered a prosthodontic procedure to one which marries endodontic principles with sound understanding of mechanical objectives. This article presents a rationale for techniques in materials selection and post-space preparation. A review of literature is presented and practical clinical guidelines are suggested when post placement is considered the treatment of choice.